US20040181273A1 - Dilator with expandable member - Google Patents

Abstract

The invention relates to a dilator having an expandable member and relates to a dilator and access sheath assembly including a first conduit which includes a wall defining a lumen therethrough and which is sufficiently rigid to dilate tissue in a body vessel; a member coaxially surrounding a first section of the first conduit, where the member is capable of expanding; and a second conduit coaxially surrounding a second section of the first conduit.

Description

FIELD OF THE INVENTION
• The invention generally relates to dilators having an expandable member. More particularly, the invention relates to a dilator having an expandable balloon at one end for use in association with a sheath.[0001]
BACKGROUND OF THE INVENTION
• Ureteroscopy is a procedure that can be used when ureteral stones, strictures, or tumors are present. Ureteral stones are generally formed in the kidney and pass down into the ureter where they become lodged. In the ureter, stones block the passage of urine to the bladder, generating pain for a patient. Often, infection ensues, and in certain cases the infection can be life threatening. Ureteroscopy enables a surgeon to access, disintegrate, and remove ureteral stones.[0002]
• Strictures are a constriction of the ureter associated with abnormal tissue. A stricture can result for various reasons, including congenital abnormalities, previous surgery, passage of stones, or radiation therapy. Ureteroscopy allows a surgeon to locate and repair a stricture using tools, such as expandable balloons and lasers.[0003]
• Ureteroscopy also can be used when tumors are present in the ureter. Using ureteroscopy, surgeons can better diagnose the cancer by taking tissue samples. In some cases, the cancer can be treated through the use of an ureteroscopy procedure, thereby avoiding the use of more invasive techniques. Accordingly, devices and related methods are needed to allow a medical professional to undertake such procedures.[0004]
SUMMARY OF THE INVENTION
• The present invention relates to a dilator having an expandable member. The dilator is a multifunctional device as it can dilate tissue as a dilator and expand tissue as an expandable member. The dilator can be connected to an access sheath. Such devices are useful in ureteroscopy procedures. The device, however, can be used in any procedure where it is required to access and dilate any vessel, lumen, or other orifice in the body, or to bypass various types of blockages formed thereby or occurring therein.[0005]
• In an ureteroscopy procedure utilizing devices according to the invention, a medical professional inserts a guide wire through the urethra, into the bladder, through the ureteral orifice, into the ureter, and then to the kidney. Following placement of the guide wire, the medical professional slides an assembly of the access sheath and the dilator with an expandable member over the guide wire. When a blockage of the urinary tract is encountered as, for example, but without limitation, when a constriction of the ureteral orifice, a stricture, a stone, or a tumor is encountered, the medical professional can expand the expandable member on the dilator to relieve or bypass the blockage. Once the blockage has been relieved or bypassed, the medical professional can deflate the expandable member. The expandable member, because it is connected to the dilator, remains immediately available to the medical professional while the dilator remains in the lumen of the access sheath.[0006]
• Devices and methods according to the invention aid surgery because a medical professional does not have to remove the dilator according to the invention from within the access sheath, or remove the entire balloon dilator access sheath assembly according to the invention, before inserting a separate expandable member into the access sheath, or into the body vessel if the sheath is removed as well, to solve a blockage problem. This reduces the time of surgeries to the benefit of the patient and simplifies the surgical procedure to the benefit of the medical professional by decreasing the number of interventions that need to be undertaken to pass tools. Costs are also reduced, because the use of separate dilators and balloon catheters may be avoided.[0007]
• One aspect of the invention relates to a dilator and access sheath assembly. The dilator and access sheath assembly includes a first conduit where the conduit is sufficiently rigid to dilate tissue in a body vessel. The assembly also can include a member coaxially surrounding a first section of the first conduit, where the member is capable of expanding, and can include a second conduit coaxially surrounding a second section of the first conduit.[0008]
• The assembly described above can have any of the following features or characteristics. The first section can overlap the second section. Alternatively, the first and second sections can be distinct and not overlap. The first conduit can include a tapered tip. The member can include a balloon, and the balloon can be compliant or non-complaint. The assembly also can include a first hub adjacent to the first conduit and a second hub adjacent to the second conduit, where the first and second hubs are connectable. The first conduit also can include a wall defining a lumen therethrough. A passage can extend within the wall and along at least a portion of the first conduit, the passage communicating with the member. The first conduit can define two or more lumens. The assembly can also include a passage that extends along at least a portion of the first conduit, where the passage communicates with the member, and the passage can extend within the wall of the first conduit.[0009]
• Another aspect of the invention relates to a method for accessing a surgical site. The method includes inserting a dilator and access sheath assembly into a patient, the assembly including a first conduit, a member coaxially surrounding a first section of the first conduit and capable of expansion, and a second conduit coaxially surrounding a second section of the first conduit. The method also includes advancing the assembly through a body vessel to dilate the tissue of the vessel and, without the removal of the assembly from the vessel, expanding the member to alleviate a blockage in the vessel.[0010]
• The method described above can have any of the following features or characteristics. The first section can overlap the second section. Alternatively, the first and second sections can be distinct and not overlap. The first conduit can include a tapered tip. The member can be a balloon. The method also can include the further steps of unexpanding the member and advancing the assembly beyond the blockage. The blockages can include, without limitation, a constriction of the ureteral orifice, a sphincter, a stone, and a tumor.[0011]
BRIEF DESCRIPTION OF THE DRAWINGS
• The foregoing and other objects, aspects, and advantages of the invention and the various features thereof may be more fully understood from the following description when read together with the accompanying drawings. In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the technology.[0012]
• FIG. 1 depicts a schematic side section view of one embodiment of a balloon dilator access sheath assembly.[0013]
• FIG. 2 depicts a schematic cross section of the balloon dilator access sheath assembly of FIG. 1 taken along line[0014]1-1 of FIG. 1.
• FIG. 3 schematically depicts the balloon dilator access sheath assembly of FIG. 1 in use during a ureteroscopy procedure.[0015]
• FIG. 4 depicts a schematic side view of a second embodiment of a balloon dilator access sheath assembly.[0016]
• FIG. 5 depicts a schematic side section view of an enlarged portion[0017]4-4 of the assembly of FIG. 4, as shown in FIG. 4.
• FIG. 6 depicts a schematic side section view of a dilator hub of the balloon dilator access sheath assembly of FIG. 4.[0018]
• FIG. 7 depicts a schematic perspective view of the dilator hub of the balloon dilator access sheath assembly of FIG. 4.[0019]
• FIG. 8 depicts a schematic distal end view of the dilator hub of the balloon dilator access sheath assembly of FIG. 4.[0020]
• FIG. 9 depicts a schematic proximal end view of the dilator hub of the balloon dilator access sheath assembly of FIG. 4.[0021]
• FIG. 10 depicts a schematic top view of an access sheath hub of the balloon dilator access sheath assembly of FIG. 4.[0022]
• FIG. 11 depicts a schematic cross section view of the access sheath hub of FIG. 10 taken along line[0023]10-10 of FIG. 10.
• FIG. 12 depicts a schematic side view of the access sheath hub of the balloon dilator access sheath assembly of FIG. 4.[0024]
• FIG. 13 depicts a schematic cross section view of the access sheath hub of FIG. 12 taken along line[0025]12-12 of FIG. 12.
• FIG. 14 depicts a schematic side view of the access sheath hub of FIG. 12 rotated 90 degrees about its longitudinal axis.[0026]
• FIG. 15 represents a schematic distal end view of the access sheath hub of FIG. 14.[0027]
• FIG. 15A depicts a schematic cross section view of the dilator hub of the balloon dilator access sheath assembly of FIG. 4 connected to the access sheath hub of the same assembly.[0028]
• FIG. 16 depicts various size configurations for the second embodiment of the balloon dilator access sheath assembly.[0029]
• FIG. 17 depicts the results of a three point bend stiffness test conducted on balloon dilator access sheath assemblies of the present invention.[0030]
• FIG. 18 depicts the results of a three point bend stiffness test conducted on balloon dilator access sheath assemblies of the present invention.[0031]
DETAILED DESCRIPTION OF THE INVENTION
• The present invention relates to a dilator having an expandable member. The dilator can be used with an access sheath in various surgical procedures requiring access, through, for example, a vessel in the body. Ureteroscopy procedures are a non-limiting example of such procedures. Other procedures include an endopyelotomy procedure to treat a uretero-pelvic junction obstruction, the treatment of urethral strictures, percutaneous renal surgery, and vascular access surgery.[0032]
• In an ureteroscopy procedure, a guide wire is introduced into the urethra. The wire then is fed through the urinary tract into the bladder. From the bladder, the wire passes through the ureteral orifice and into the ureter. If access to the kidney is required, the wire is fed through the ureter, to the kidney, where its distal end can be lodged.[0033]
• In current ureteroscopy procedures, after introducing the guide wire, a medical professional has several choices. In a first method, the medical professional can introduce a dilating element that is connected to a surrounding sheath over the guide wire. As the dilating element is introduced over the guide wire, the dilating element radially expands the tissue of the urinary tract. After the dilator with the connected surrounding sheath has been guided to its required destination, the dilating element is detached from the sheath and removed from the lumen of the sheath, leaving the sheath in place. In a second method, after the guide wire is introduced, a medical professional can slide a sheath that also functions as a dilating element over the length of the guide wire. This type of device generally has a tapered tip to gradually dilate tissue.[0034]
• Medical professionals performing ureteroscopy procedures sometimes encounter difficulties gaining access to various parts of the urinary tract because of a blockage of the urinary tract, for example, but without limitation, a constriction of the ureteral orifice, which is situated between the bladder and the ureter, a stricture, a stone, or a tumor. If the first method, as described above, is used to access the ureter, it may be necessary to use a balloon to expand the tissue of the ureteral orifice to enable the sheath to enter the ureter. This requires, for example, that the medical professional remove the dilating element from the lumen of the sheath and, then, introduce the balloon into the lumen. The balloon is then used to expand the tissue of the ureteral orifice, and then the sheath is advanced through the ureteral orifice. Once the sheath has passed through the ureteral orifice into the ureter, the balloon is removed from the sheath, and other tools, such as the dilating element, are re-introduced into the sheath's lumen to continue the procedure being conducted. Alternatively, if a balloon is not used, the dilating element may be forced through the ureteral orifice, potentially damaging the orifice. If access to the ureteral orifice is not possible, then the patient may have to undergo a more invasive procedure, such as percutaneous access or open surgery. Likewise, if the second method, as described above, is used to access the ureter and a balloon is required to expand the ureteral orifice, the medical professional will need to remove the sheath/dilator device from the patient before inserting a balloon into the patient. Once the blockage has been overcome, the balloon is removed from the body, and the dilator/sheath device is re-inserted into the patient. This method also has the disadvantage that the passage held open by the sheath must be re-established each time the dilator/sheath device is reinserted into the patient.[0035]
• In addition to being unable to access the ureteral orifice, other problems encountered by medical professionals which hinder the passage of the sheath are the presence of strictures, stones, or tumors in the ureter. In this situation, if the first method of accessing the ureter is used as described above, upon encountering the stricture, stone, or tumor, the dilating element is removed from the sheath, and a balloon is introduced through the lumen of the sheath to expand the passage. Potentially, other tools, such as a lithotriptor or a grasper, may need to be used as well to reduce, remove, or bypass the obstruction. Once the stricture, stone or tumor is relieved or bypassed, the balloon is removed from the sheath, and other tools, such as the dilating element, are re-introduced into the sheath. If the second method as described above is used to access the ureter, and the dilator/sheath device is incapable of bypassing the stricture, stone or tumor, the dilator/sheath device is removed from the body, and a balloon is inserted to expand the passage. Once the stricture, stone or tumor is bypassed, the balloon is removed from the body, and the dilator/sheath device is re-introduced.[0036]
• Accordingly, dilators of the invention have the functionality of both a dilating element and an expandable member, such as a balloon, in the same device. One advantage of combining these functions in a single device is that a medical professional does not have to remove a dilator from a sheath before inserting an expandable member in order to, for example, remove a blockage. This reduces the time of surgery to the benefit of the patient, and simplifies the surgical procedure for the benefit of the medical professional. Moreover, costs are reduced, because the need for a separate dilator and an expandable member is avoided. Furthermore, when the dilator having an expandable member is used with an access sheath, additional benefits are realized. For instance, the access sheath protects tissue from damage when tools and instruments, such as lasers, graspers, lithotriptors, scopes, and dilators according to the invention are passed through the lumen of the access sheath, which reduces healing time for the patient. The access sheath also improves irrigation, which can enhance visibility for the medical professional.[0037]
• Now, referring to FIGS. 1 and 2, a balloon dilator[0038]access sheath assembly2 according to the invention includes adilator4 having aproximal end6 and a distal end8 (As used herein, “proximal” refers to the end of the device closest to a medical professional during use of the device and “distal” refers to the end of the device furthest from the medical professional during use). Awall21 of thedilator4 defines a lumen therethrough10. Alternatively, the dilator can be solid and utilized without a guide wire. The balloon dilatoraccess sheath assembly2 also includes anaccess sheath30 which is coaxial with and surrounds thedilator4, when assembled. Thedilator4 is sufficiently rigid along its length to perform its dilation function. Such rigidity typically is greater than expansion devices, including balloon expanders, used in the art. This allows thedilator4 to dilate tissue without buckling. For example, the dilator can be made from a material having a durometer value of about 40 to about 80 on a Shore A scale, about 45 to about 75 on a Shore A scale, about 50 to about 70 on a Shore A scale, or about 55 to about 65 on a Shore A scale. These durometers are sufficiently hard so that the dilator is sufficiently rigid to dilate tissue in a body vessel. The thickness of the wall of the dilator also can be varied to create sufficient rigidity, and/or reinforcing materials can be used. Further examples of rigidity are discussed below. The dilator can be manufactured using an extrusion process and can be made from, for example, but without limitation, polyethylene, such as polyethylene having a molecular weight in the range of 50,000 to 100,000; nylon, such asnylon 12, nylon 4-6, and nylon 6-6; Pebax (polyether block amides), for example having a durometer value of about 72 to about 85 on a Shore D scale; polyurethane, for example having a durometer value of about 75 on a Shore D scale; polytetrafluoroethylene (PTFE), particularly fluorinated ethylene propylene (FEP) copolymers; and polyethylene impregnated with PTFE. In certain embodiments, the dilator is made from materials with a flex modulus of about 300 to about 500 MPa.
• The external surface of the dilator can have a hydrophilic coating or a silicone coating to ease the passage of the dilator in tissue. Such a hydrophilic coating can be, for example, but without limitation, N-Vinyl Pyrrolidone, Poly Vinyl Alcohol, and Poly Vinyl Pyrrolidone. The hydrophilic coating can be accomplished by coating a device with a primer, such as Bayhydrol[0039]110 (an anionic dispersion of an aliphatic polyester urethane resin in water/n-methyl-2-pyrrolidone) and then bonding a primary layer over the primer. The primary layer can be, without limitation, an acrylamide or a polyurethane-based acrylamide. Alliphatic polyether and polyester polyurethanes also can be used as lubricous coatings.
• Located at the[0040]proximal end6 of thedilator4 is ahub12. Thehub12, in this embodiment, is a bi-furcated hub. Located near thedistal end8 of thedilator4 is anexpandable member14. Theexpandable member14 surrounds thedilator4 and is coaxial with thedilator4. In this embodiment, theexpandable member14 is a low profile, high-pressure balloon. The balloon can be compliant or non-compliant and can be made from, for example, but without limitation, nylon, polyethylene terephthalate (PET), polyethylene, polyurethane, Pebax, silicone, or latex. Alternatively, the expandable member can be, for example, several balloons, expandable metal elements, sequential fascial PTFE dilators, single step fascial PTFE dilators, an inverse Chinese finger, cutting balloons, or a braided cage.
• The[0041]expandable member14 is connected to thedilator4. The connection can be accomplished by bondingballoon necks16, which are coaxial with thedilator4, to the outer surface of thedilator4. Theballoon necks16 have substantially the same inner diameter as the outer diameter of thedilator4. Such an expandable member can be formed through a blow molding process and then can be fitted over the dilator. Briefly, in the blow molding process, a section of tubing is expanded about its middle section, leaving the ends (i.e., the balloon necks16) unexpanded. The section of tubing then is slid over the dilator to its proper position, and the balloon necks are connected to the dilator. Connection can be accomplished through the use of an adhesive bond, through the use of a shrink fit bond, through the use of an RF bond, through the use of an ultrasonic bond, through the use of a laser bond, or through the use of an interference fit.
• The[0042]distal end8 of thedilator4 has a taperedtip18. The taperedtip18 is integral with thedilator4. Alternatively, the tapered tip can be a separate part that is designed to mate with the dilator using any technique known in the art, such as, but without limitation, a press fit, a snap fit, or threading.
• When the balloon dilator[0043]access sheath assembly2 is assembled, theaccess sheath30, having a circular cross section, is coaxial with and surrounds thedilator4. Alternatively, the access sheath (and/or dilator) can have an oval cross section. Theaccess sheath30 has aproximal end32 and adistal end34 defining a length therebetween. Generally, theaccess sheath30 is less rigid thandilator4, but sufficiently rigid to avoid buckling, and may be formed using an extrusion process. For example, theaccess sheath30 can be made from a material having a durometer value of about 30 to about 50 on a Shore A scale or about 35 to about 45 on a Shore A scale. The wall of theaccess sheath30 can also be varied in thickness to vary rigidity, and/or reinforcing materials can be used. Further examples of rigidity are discussed below. To reduce friction when theaccess sheath30 is introduced into the body, theaccess sheath30 can have a hydrophilic coating, such as those described above. Additionally, theaccess sheath30 can be coated or be formed integrally with one or more agents to provide, for example, an anti-inflammatory, analgesic, anti-spasmodic, or anti-microbial effect, alone or in combination, when inserting or upon insertion of the access sheath. Other types of agents are contemplated within the scope of invention for use as a coating on the access sheath or within the access sheath to provide a therapeutic or healing effect. For example, but without limitation, Toradol (ketorolac tromethamine), or Ditropan (oxybutynin chloride), may be incorporated on or into the access sheath to aid healing of urinary tract tissue or to relieve discomfort.
• The access sheath can be manufactured from one layer of material or from multiple overlaid or fused layers of the same or different materials, and may or may not include a reinforcing member to increase column strength. For example, an inner surface of the access sheath can comprise, for example, PTFE, or, as another example, Pebax. The reinforcing member can be a stainless steel coil, and the outer surface can comprise, for example, Pebax, or, as another example, Hytrel (a polyether ester elastomer block copolymer consisting of a hard crystalline segment of polybutylene terephthalate and soft amorphous segments based on long-chain polyether glycols). In some cases, a tie layer exists between the inner PTFE surface and the outer Pebax or Hytrel surface. When Pebax is used as an inner or outer surface, Pebax having a durometer value of about 45 to about 72 on a Shore D scale can be used. The access sheath also can be made from polyurethanes having a durometer value of about 45 to about 72 on a shore D scale, nylons, or PTFE impregnated with either Pebax or nylons.[0044]
• When the[0045]access sheath30 and thedilator4 are in use, thedistal end34 of theaccess sheath30 is spaced apart from theexpandable member14. Alternatively, the distal end of the access sheath can partially or fully cover the expandable member.
• The[0046]access sheath30 is connected to ahub33 at itsproximal end32. In use, thehub12 of thedilator4 is received within thehub33 of theaccess sheath30, and thehubs12,33 connect. In certain embodiments, thehubs12,33 can connect through the use of a friction fit, snap-fit or a compression fit, or by locking, or twisting. During use, thehub33 of theaccess sheath30 holds thehub12 of thedilator4 securely in place, such that movement of thedilator4 relative to theaccess sheath30 is minimal or non-existent. Once use of thedilator4 is no longer required, thedilator4 can be disconnected and removed from theaccess sheath30, leaving theaccess sheath30 in place.
• FIG. 2 is a cross section of the balloon dilator[0047]access sheath assembly2 taken along line1-1 in FIG. 1. Thedilator4 has awall21 defining alumen10. Thewall21 includes aninner wall20 and anouter wall22 defining asolid area24 therebetween. Within thesolid area24, there is apassage26 that extends from theexpandable member14 towards theproximal end6 of thedilator4. At its distal end, thepassage26 communicates with theexpandable member14. An aperture, for example, through theouter wall22 of thedilator4 allows communication between thepassage26 and the interior of theexpandable member14. At its proximal end, thepassage26 is accessible to the medical professional through aballoon luer39.
• The[0048]expandable member14 can be inflated by a medical professional by introducing a gas or a liquid, for example, a saline solution, a saline solution mixed with a radioactive isotope, which is useful in radiation treatment, or a saline solution mixed with radiopaque material, into thepassage26 at its proximal end through theballoon luer39. A syringe can be used to introduce liquid into thepassage26 via theballoon luer39, or, if a gas is used, an inflator can be used to introduce a controlled volume of gas into thepassage26 through theballoon luer39. The gas or liquid then travels along the length of thepassage26 to the passage's distal end. Because theexpandable member14 and the distal end of thepassage26 are in communication, when the gas or liquid arrives at the distal portion of thepassage26, the gas or liquid enters the interior of theexpandable member14 through, for example, the aperture between thepassage26 and theexpandable member14. The buildup of pressure within theexpandable member14 causes theexpandable member14 to expand. The medical professional can control the amount of expansion by controlling the amount of liquid or gas introduced into thepassage26, for example, by using a syringe or inflator that includes a pressure gauge. Likewise, to deflate theexpandable member14, the medical professional can remove fluid or gas from thepassage26 and/or theexpandable member14 through theballoon luer39. This causes a reduction in pressure within thepassage26 and/orexpandable member14 and allows theexpandable member14 to deflate. As a general principle, the medical professional applies a force to theexpandable member14 through thepassage26, expanding the expandable member. To deflate the expandable member, the medical professional removes the force.
• In another embodiment, the dilator can have two or more separate lumens. One of the lumens communicates with the expandable member through an aperture in the wall of the dilator. In some embodiments, this lumen ends immediately distal to the aperture, which is proximal to the distal end of the dilator. This lumen also can be smaller than the other lumens. Alternatively, more than one lumen of the dilator communicates with the expandable member. A force is applied to expand the expandable member, for example, using a gas or a liquid, as described above.[0049]
• Now referring to FIG. 3, in an ureteroscopy procedure according to the invention, the patient can be given local or general anesthetic. A guide wire then is introduced into the[0050]urethra50 and is fed through thebladder52,ureteral orifice54, andureter56 to thekidney58. The proximal end of the guide wire then is introduced into thetip18 of the balloon dilatoraccess sheath assembly2 such that the balloon dilatoraccess sheath assembly2 slides over the guide wire. Thetip18 of thedilator4 is advanced to the orifice of the urethra. As thetip18 of thedilator4 moves along theurethra50, it applies radial pressure to the tissue of the urinary tract, gradually dilating such tissue. Gradual dilation reduces trauma to the patient. The taperedtip18 of thedilator4 facilitates, in part, such gradual dilation. Dilating the urinary tract allows theaccess sheath30 of the balloon dilatoraccess sheath assembly2 to be inserted into the body.
• Once the balloon dilator[0051]access sheath assembly2 reaches theureteral orifice54, the balloon dilatoraccess sheath assembly2 must be guided through theureteral orifice54, which can be difficult. Sometimes, the orifice is constricted, and theexpandable member14 is used to open theureteral orifice54. The medical professional expands theexpandable member14, opening theureteral orifice54, which allows access to theureter56. Theexpandable member14 is then deflated, and the balloon dilatoraccess sheath assembly2 is advanced into theureter56. As can be seen, this procedure and device allows the medical professional to utilize both the dilating and expansion functionality of thedilator4. Moreover, the medical professional does not need to remove thedilator4 or the entire balloon dilatoraccess sheath assembly2 to replace it with a separate expandable member.
• Alternatively, or in addition, use of the balloon dilator[0052]access sheath assembly2 may be required should a stone, tumor, or stricture be encountered in the ureter. Again, in the same manner described above, the medical professional would expand theexpandable member14 to bypass the obstruction, and then theexpandable member14 would be contracted. The balloon dilatoraccess sheath assembly2 would then be further guided to its required destination. Once the balloon dilatoraccess sheath assembly2 is located at the desired location, thedilator4 is disconnected from theaccess sheath30 and removed from the lumen of theaccess sheath30, thereby allowing other tools to be inserted into the lumen.
• In addition to the uses described above, the[0053]expandable member14 can be used as a placement guide. In this use, thetip18 of thedilator4 is guided through theureter56, to the renal pelvis of the kidney. At the renal pelvis, theexpandable member14 is inflated. The medical professional then gently pulls the balloon dilatoraccess sheath assembly2 proximally, such thatexpandable member14 lodges in the renal pelvis. Lodging of theexpandable member14 in the renal pelvis indicates to the medical professional that the balloon dilatoraccess sheath assembly2 is properly placed. Once the balloon dilatoraccess sheath assembly2 is properly placed, theexpandable member14 is deflated, and thedilator4 is removed from the lumen of theaccess sheath30.
• Now, referring to FIGS. 4 and 5, an embodiment of the invention is illustrated, with reference to dimensions of the dilator and access sheath which may be particularly suited to application of the balloon dilator access sheath assembly in a ureteroscopy application. This embodiment may be used by a medical professional in the same manner as described above for the embodiment shown in FIGS. 1-3. The dimensions here are not intended to be restrictive, but are merely illustrative of one embodiment of the invention. In this embodiment, the balloon dilator[0054]access sheath assembly102 includes adilator104 having aproximal end106 and adistal end108 defining a length H therebetween. The length H of the dilator can range from approximately 12.065 inches to approximately 19.288 inches. The wall of thedilator104 defines alumen100 therethrough. The balloon dilatoraccess sheath assembly102 also includes anaccess sheath130 that is coaxial with and surrounds thedilator104. The dilator can be manufactured using an extrusion process and can be made from a mixture of low density polyethylene, with approximately 20% barium sulfate. Alternatively, the dilator can be made from the materials described above in the first embodiment shown in FIGS. 1-3 and can also have a hydrophilic coating. Thedilator104 is sufficiently rigid along its length to perform its dilation function without buckling. For example, thedilator104 can be made from a material having a durometer value of about 40 to about 80 on a Shore A scale, about 45 to about 75 on a Shore A scale, about 50 to about 70 on a Shore A scale, or about 55 to about 65 on a Shore A scale. These durometers are sufficiently hard so that thedilator104 is sufficiently rigid to dilate tissue in a body vessel. The thickness of the wall of thedilator104 also can be varied to create sufficient rigidity, and/or reinforcing materials can be used. Further examples of rigidity are discussed below.
• The[0055]proximal end106 of thedilator104 is connected to ahub112, which is designed to fit in abore168 of ahub133 of theaccess sheath130. Located near thedistal end108 of thedilator104 is an expandable member114 (a balloon), which surrounds thedilator104 and is coaxial with thedilator104. Theexpandable member114 can have any of the features described in the embodiment shown in FIGS. 1-3, and can be constructed and connected to the dilator using any technique previously described.
• The[0056]dilator104 has a wall which defines a solid area between its inner and outer diameters. Within the solid area, there is a passage that extends longitudinally from theexpandable member114 towards theproximal end106 of thedilator104. At its distal end, the passage communicates with theexpandable member114. An aperture, for example, through the wall of thedilator104 allows communication between the passage and the interior of theexpandable member114. At its proximal end, the passage is accessible to the medical professional, allowing theexpandable member114 to be inflated and deflated as described in the embodiment shown in FIGS. 1-3.
• Still referring to FIGS. 4 and 5, the[0057]distal end108 of thedilator104 also has a taperedtip118. The taperedtip118 is integral with thedilator104. In certain circumstances, the taperedtip118 can have a length J of 0.755 inches and an exposed tip length K of 1.11 inches. The taperedtip118 can have at its distal most end an inner diameter D of 0.042 inches and an outer diameter E of 0.066 inches. In these circumstances, proximal to the taperedtip118, the dilator's104 outer diameter F can be 0.142 inches and its inner diameter G can be 0.98 inches, the sheath tip inner diameter B can be 0.139 inches, and the sheath outer diameter C can be 0.172 inches. In other circumstances, the taperedtip118 can have a length J of 0.895 inches and at itsdistal end108 can have an inner diameter D of 0.042 inches and an outer diameter E of 0.066 inches. In these circumstances, proximal to the taperedtip118, thedilator104 can have an outer diameter F of 0.170 inches and an inner diameter G of 0.122 inches, the sheath tip inner diameter B can be 0.167 inches, and the sheath outer diameter C can be 0.200 inches. In this circumstance, the exposed tip length K of thedilator104 can be 2.807 inches.
• When the[0058]assembly102 is assembled, theaccess sheath130, having a circular cross section, is coaxial with and surrounds thedilator104. Theaccess sheath130 has aproximal end132 and adistal end134 defining a length A therebetween. In this embodiment, thedistal end134 of theaccess sheath130 ends proximal to thedistal end108 of thedilator104, such that there is an exposed tip length K of thedilator104 that is not surrounded by theaccess sheath130. Theaccess sheath130 can have a sheath working length A ranging from about 10.0 to 19.0 inches.
• The[0059]access sheath130 is less rigid thandilator104, but sufficiently rigid to avoid buckling. For example, theaccess sheath130 can be made from a material having a durometer value of about 30 to about 50 on a Shore A scale or about 35 to about 45 on a Shore A scale. The wall of theaccess sheath130 can also be varied in thickness to vary rigidity, and/or reinforcing materials can be used. Further examples of rigidity are discussed below. In this embodiment, theaccess sheath130 comprises a reinforcing member incorporated into the wall of theaccess sheath130. The outer surface layer of theaccess sheath130 can be made from Pebax, and the inner surface layer of theaccess sheath130 can be made from PTFE. Alternatively, any materials described in the embodiment in FIGS. 1-3 for the construction of the access sheath can be used in this embodiment. The reinforcing member incorporated in theaccess sheath130 is a rolled flat wire spring, which increases the column strength of theaccess sheath130. Further, the access sheath can be coated or manufactured to include, for example, but without limitation to, one or more agents, such as Toradol, as described above with respect to the embodiment in FIGS. 1-3.
• Turning now to FIGS. 6, 7,[0060]8 and9, thehub112 of thedilator104 according to this embodiment is shown in greater detail. Thehub112 is made from Delrin (an acetal homopolymer), using an injection molding process. Thehub112 defines a generallycylindrical bore150 which extends longitudinally through thehub112 from adistal end151 of thehub112 to aproximal end152. In this embodiment, thehub112 and thedilator104 are created as an integral device using injection molding manufacturing. Alternatively, if the parts are made separately, thedilator104 can be received in thebore150 of thehub112 at thedistal end151 of thehub112, and connected to thehub112 using any technique known in the art, for example, threading or by the use of an adhesive. Located at theproximal end152 of thehub112 is a luer lock fitting155 which is integral with thehub112. Alternatively, the luer lock fitting can be a separate part that is connected to the hub using, for example, but without limitation, an adhesive bond, or by threading. In use, the luer lock fitting155 provides a means for the medical professional to attach other medical equipment, such as a drainage tube, to thehub112 of thedilator104. Alternatively, during use, a contrasting fluid can be injected through the luer lock fitting155 to aid the medical professional in the procedure being conducted. Thehub112 also includes atab156 on its bottom portion. Located on thetab156 is aprotrusion157 which allows thehub112 of the dilator to snap fit into thehub133 of theaccess sheath130. Located at the top portion of thedilator hub112, is asemicircular flange159 which abuts theproximal end164 of thehub133 of theaccess sheath130 when thehub112 of thedilator104 is connected to thehub133. Theflange159 prevents thehub112 from sliding distally when thedilator104 is in the lumen of theaccess sheath130. In this embodiment, the length L of thehub112 can be made to measure, so that thehub112 of thedilator104 can be received in thebore168 of thehub133 of theaccess sheath130.
• Turning to FIGS. 10 through 15, the[0061]hub133 of theaccess sheath130 is shown in greater detail. Thehub133 is generally tubular in shape and has aproximal end164 and adistal end166. In this embodiment, thehub133 can have a length L1 of approximately 1.17 inches, and can be made from Pebax in an injection molding process. The interior of thehub133 defines abore168. Thebore168 is widest at theproximal end164 of thehub133 and gradually tapers towards thedistal end166 of thehub133, into a generallycylindrical portion167. The generallycylindrical portion167 has a diameter that is approximately equivalent to the outer diameter of theaccess sheath130. In this embodiment, theaccess sheath130 is injection molded with thehub133 to create an integral device. Alternatively, thehub133 and theaccess sheath130 can be made as separate parts. In this circumstance, theaccess sheath130 can be connected to thehub133 by sliding theaccess sheath130 into thehub133 at itsdistal end166. Theaccess sheath130 is then connected to theinner wall169 of thebore168 along its generallycylindrical portion167 using any technique known in the art, such as adhesive bonding or threading. At theproximal end164 of thehub133, thebore168 of thehub133 has anorifice170 through which thehub112 of thedilator104 can be received. Theorifice170 can, for example, have a diameter D1 of 0.595 inches. Also at theproximal end164 of thehub133 is alocking mechanism162, which extends slightly radially into thebore168 of thehub133. In use thelocking mechanism162 receives theprotrusion157 of thetab156 of thehub112 of thedilator104, which connects thehub112 of thedilator104 to thehub133 of theaccess sheath130. Referring to FIG. 13, thehub133 of theaccess sheath130 also includes a pair of throughholes174 located on aportion176. In use, the throughholes174 on theportion176 can be used to suture thehub133 of theaccess sheath130 to surgical drapes.
• In use, as shown in FIG. 15A, the[0062]hub112 of thedilator104 is received by thehub133 of theaccess sheath130, and thehubs112,133 connect. The connection between thehubs112,133 is tight, minimizing or eliminating altogether the relative movement between thedilator104 and theaccess sheath130. More specifically, to insert thehub112 of thedilator104 into theaccess sheath hub133, a medical professional introduces thetip118 of thedilator104 into thebore168 of thehub133 of theaccess sheath130, and gradually slides thedilator104 distally into theaccess sheath130. To place thehub112 of thedilator104 into thebore168 of thehub133, the medical professional squeezes thetab156 of thehub112 slightly upwardly, and slides thehub112 of thedilator104 into thebore168 of thehub133 of theaccess sheath130 until theflange159 abuts thedistal end164 of thehub133. When theflange159 abuts thedistal end164 of thehub133, the medical professional releases thetab156 and theprotrusion157 on thetab156 snaps into thelocking mechanism162, preventing thehub112 from sliding proximally out of thehub133.
• Once use of the[0063]dilator104 is no longer required, thedilator104 can be disconnected, and removed from theaccess sheath130, leaving theaccess sheath130 in place. To remove thedilator104, the medical professional squeezes thetab156 of thehub112 of thedilator104, and slides thehub112 of thedilator104 slightly distally to release theprotrusion157 from thelocking mechanism162. Thehub112 of thedilator104 can then be slid proximally, thereby removing thehub112, and eventually thedilator104, from thehub133 of theaccess sheath130.
• Referring to FIG. 16, the balloon dilator[0064]access sheath assembly102 can be created in several different size configurations. The dimensions here are not intended to be restrictive, but are merely illustrative of exemplary embodiments of the invention. Unless otherwise noted, the dimensions in FIG. 16 are in inches. The notation “O.D.” refers to outer diameter, and the notation “I.D.” refers to inner diameter. Each row of FIG. 16 contains a different aspect of the device. For example, the device shown inrow1 has a sheath working length A of 10.94 inches, with a sheath tip inner diameter B of 0.139 inches, a sheath outer diameter C of 0.172 inches, a dilator tip inner diameter D of 0.042 inches, a dilator tip outer diameter E of 0.066 inches, a dilator body outer diameter F of 0.142 inches, a dilator body inner diameter G of 0.098 inches, and a dilator working length H of 12.065 inches. The length J of the tapered portion of thedilator tip118 is 0.755 inches, and the exposed tip length K of thedilator104 is 1.11 inches.
• As described above, a dilator according to the invention and/or a balloon dilator access sheath assembly according to the invention can have sufficient rigidity to dilate tissue in a body vessel. Referring to FIGS. 17 and 18, when the balloon dilator access sheath assembly (or a dilator according to the invention) is tested for rigidity, a three point bend stiffness test can be utilized. The purpose of the three point bend stiffness test is to measure the force required for a push rod to travel a certain distance when the push rod pushes on the balloon dilator access sheath assembly, thereby bending the balloon dilator access sheath assembly. In the test, the balloon dilator access sheath assembly is supported by a pair of holders spaced two inches apart. A push rod having a radius of 0.159 inches is then used to apply a force to the midpoint of the supported section of the balloon dilator access sheath assembly such that the force applied is sufficient to move the push rod a reference distance of 0.375 inches. All of the tests are conducted at ambient conditions. The force measurements in FIGS. 17 and 18 are given in pounds-force (lbf) while the dimensions are given in inches. The notation “O.D.” refers to outer diameter, and the notation “I.D.” refers to inner diameter.[0065]
• The rigidity measurements in FIG. 17 indicate that the tested balloon dilator access sheath assemblies, such as those described above, have sufficient rigidity to dilate tissue in a body vessel. The force measurements here are not intended to be restrictive, but are merely illustrative of exemplary embodiments of the invention. In FIG. 17, assemblies having a dilator with an 11 French outer diameter and an access sheath with a 13 French outer diameter were tested. Three different sized dilators, each having a different sized inner diameter, were used with the same sized access sheath. The inner diameters of the dilators tested were 0.098 inches, 0.082 inches, and 0.060 inches. Each row of FIG. 17 contains a different sample of the assembly that was tested. For example, the first sample was three assemblies. The first assembly tested included a dilator having an inner diameter of 0.098 inches, and a force of 1.39 lbf was required to move the push rod the reference distance. The second assembly tested included a dilator with an inner diameter of 0.082 inches, and a force of 1.62 lbf was required to move the rod the reference distance. The third assembly tested included a dilator with an inner diameter of 0.060 inches, and a force of 1.75 lbf was required to move the push rod the reference distance. The bottom rows of FIG. 17 show the average force, minimum force, and maximum force required to move the push rod the reference distance for each of the six assembly samples tested for each of the three different dilator inner diameter sizes. For example, when a dilator with an inner diameter of 0.098 inches was tested, the average force across the six assembly samples required to move the push rod the reference distance was 1.49 lbf, the maximum force was 1.67 lbf, and the minimum force was 1.25 lbf.[0066]
• In FIG. 18, assemblies having a dilator with a 13 French outer diameter and an access sheath with a 15 French outer diameter were tested. Three different sized dilators, each having a different sized inner diameter, were used with the same sized access sheath. The inner diameters of the dilators tested were 0.122 inches, 0.090 inches, and 0.110 inches. Each row of FIG. 18 contains a different sample of the assembly that was tested. For example, the first sample was three assemblies. The first assembly tested included a dilator having an inner diameter of 0.122 inches, and a force of 1.60 lbf was required to move the push rod the reference distance. The second assembly tested included a dilator with an inner diameter of 0.090 inches, and a force of 2.02 lbf was required to move the rod the reference distance. The third assembly tested included a dilator with an inner diameter of 0.110 inches, and a force of 1.80 lbf was required to move the push rod the reference distance. The bottom rows of FIG. 18 show the average force, minimum force, and maximum force required to move the push rod the reference distance for each of the six assembly samples tested for each of the three different dilator inner diameter sizes. For example, when a dilator with an inner diameter of 0.122 inches was tested, the average force across the six assembly samples required to move the push rod the reference distance was 1.73 lbf, the maximum force was 1.83 lbf, and the minimum force was 1.60 lbf.[0067]
• While the invention has been shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. It should be further reiterated that this device is not limited to use in ureteroscopy procedures, but can also be used to access other vessels and orifices of the body.[0068]

Claims (16)

What is claimed is:

1. A dilator and access sheath assembly comprising:

(a) a first conduit being sufficiently rigid to dilate tissue in a body vessel;

(b) a member coaxially surrounding a first section of the first conduit, wherein the member is capable of expanding; and

(c) a second conduit coaxially surrounding a second section of the first conduit.

2. The assembly ofclaim 1 wherein the first conduit comprises a tapered tip.

3. The assembly ofclaim 1 wherein the member comprises a balloon.

4. The balloon ofclaim 3 wherein the balloon is compliant.

5. The assembly ofclaim 3 wherein the balloon is non-compliant.

6. The assembly ofclaim 1 further comprising a first hub adjacent to the first conduit and a second hub adjacent to the second conduit, wherein the first and second hubs are connectable.

7. The assembly ofclaim 1 wherein the first conduit further comprises a wall defining a lumen therethrough.

8. The assembly ofclaim 7 wherein a passage extends within the wall and along at least a portion of the first conduit, the passage communicating with the member.

9. The assembly ofclaim 1 wherein the first conduit defines two or more lumens.

10. The assembly ofclaim 1 wherein a passage extends along at least a portion of the first conduit, the passage communicating with the member.

11. The assembly ofclaim 10 wherein the passage extends within the wall of the first conduit.

12. A method for accessing a surgical site comprising the steps of:

(a) inserting a dilator and sheath access assembly into a patient, the assembly comprising a first conduit, a member coaxially surrounding a first section of the first conduit and capable of expansion, and a second conduit coaxially surrounding a second section of the first conduit;

(b) advancing the assembly through a body vessel to dilate tissue of the body vessel;

and, without removal of the assembly from the vessel,

(c) expanding the member to alleviate a blockage in the vessel.

13. The method ofclaim 12 wherein the first conduit comprises a tapered tip.

14. The method ofclaim 12 wherein the member comprises a balloon.

15. The method ofclaim 12 further comprising the steps of unexpanding the member and advancing the assembly beyond the blockage.

16. The method ofclaim 12 wherein the blockage is selected from the group selected from a constriction of the ureteral orifice, a sphincter, a stone, and a tumor.

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